This program project has research components: I. Clinical Epidemiology and Pathogenesis of Gonococcal Infections: Methods include auxo-typing, outer membrane protein typing, and fluorescent antibody typing, phagocytosis of gonococci by human polymorphonuclear leukocytes, and use of antigen-specific opsonizing antibody and bactericidal antibody. II. Genetic Studies of Neisseria gonorrhoeae: The general purpose of the proposed research is to study the genetic organization of the gonococcus, Neisseria gonorrhoeae, as well as other microorganisms that cause significant sexually transmitted diseases. The thrust of our research is aimed at recognizing the nature of the determinants that contribute to bacterial virulence. By using classical genetic methods coupled with the newer techniques of recombinant DNA research we have been characterizing the pili genes of the gonococcus. We hope to better understand the precise role by which pili permit gonococci to attach to epithelial cells of susceptible tissues. In another vein, we have shown that a plasmid species is common to all strains of chlamydia. It is possible that this plasmid encodes for a polypeptide important in the pathogenesis of chlamydial disease. III. Nonogonoccal Urethritis and Related Infections: The etiology of chlamydia-negative nongonococcal urethritis, and the clinical spectrum and immunology of chlamydia trachomatis infectons are being studied. IV. Treatment and Pathogenesis of Hemophilus vaginalis Infection: The role of H. vaginalis and anaerobic bacteria in the etiology and pathogenesis of nonspecific vaginitis, and the optimal methods for therapy of this infection are being studied.